Add Actionbase to Database section

[em3s]

Add Actionbase - a database for user interactions (likes, views, follows) with precomputed reads, built on HBase.

• Core written in Java, server in Kotlin
• GitHub: https://github.com/kakao/actionbase
• Docs: https://actionbase.io

[akullpp]

It's a DB written in Kotlin/Java, how does it related to the Java PL?

[em3s]

Fair point — currently Actionbase runs as a standalone server, so it's not directly usable as a Java library. We're working on making the core embeddable as a Java library. Will open a new PR when that's ready.